Dr. Judine Davis, who sees patients at Sisters OB/GYN Center, has treated women who have the same acute morning sickness that caused Duchess Catherine to be hospitalized this year.

She explains, "It's not your everyday morning sickness that most pregnant people get. This is morning sickness morning, noon and night. This is constant vomiting. They are unable to hold anything down. It's waking them up from sleep."

Patients who are treated for acute morning sickness lose about 5% of their body weight.

Patients usually present with the condition in the Emergency Room, where they are given IV fluids. They are admitted to the hospital, and over a few days, their diet is increased until they are able to hold food without the aid of IV fluids.

By the time Duchess Catherine reaches 20 weeks, Dr. Davis says that the acute morning sickness should be well behind her. "By the fourth and fifth month, this really tapers off."